1. Field of the Invention
The present invention relates to a method for fabricating a copper/indium/gallium/selenium solar cell, and more specifically to a method for fabricating a copper/indium/gallium/selenium solar cell by a wet process under non-vacuum condition.
2. The Prior Arts
Since a copper/indium/gallium/selenium (CIGS) solar cell has high conversion efficiency, for example, the conversion efficiency of unit cell is up to 20%, and the conversion efficiency of solar cell module is also up to 14%, such that CIGS solar cells receive significant attention from the solar cell industry, and more particularly, CIGS solar cell is not restricted by the upstream raw materials.
Conventionally, the processes for fabricating CIGS solar cell generally can be divided into vacuum processes and non-vacuum processes. In vacuum processes, evaporation method and sputtering method are mainly used, and however, the expensive process equipments are requested and the efficiency of material utilization is low in vacuum processes, such that the whole fabricating cost is high. In the non-vacuum processes, the printing method and the electrodepositing method are generally used. However, the mass production of large-area solar cell is not matured, and is still stayed in the laboratory stage, so that there is no commercial large-area solar cell product in the market.
Therefore, a highly integrated non-vacuum process method is needed, and more particularly, a process in which a first transparent conducting oxide layer, a copper/indium/gallium/selenium layer, a cadmium sulfide layer, a zinc oxide layer, and a second transparent conducting oxide layer are sequentially formed on a backside electrode layer to form a CIGS solar cell with high conversion efficiency, high quality, and high reliability, and the fabricating cost is low.